External gamma-radiation dose to Syrian population based on the measurement of gamma-emitters in soils

ASSESSMENT OF RADIATION DOSE FROM INHALATION OF OUTDOOR DUST CONTAINING NATURAL RADIONUCLIDES

The 238U, 232Th and 40K concentrations were estimated in the size-fractionated urban surface deposited sediments in Ekaterinburg, Russia. The average concentrations of 238U, 232Th and 40K in dust fraction (0.002-0.05 mm) are 48 ± 7, 28 ± 1 and 510 ± 20 Bq/kg, respectively. The effective dose is estimated depending on the suggested daily scenarios of different exercises which can be assigned to light, moderate and vigorous activity. The results show that the total effective dose received during 20 years by an adult with the light activity is 5.6 μSv under exposure to air dust concentration 1 × 10-4 g/m3, which is typical for the city of Ekaterinburg. Although for the moderate and vigorous activities the total effective dose is 9.9 μSv and 48.8 μSv, respectively, during 20 years at air dust concentration equal to the diurnal Maximum Permissible Limit (1.5 × 10-4 g/m3). Thus, the effective doses due to natural radionuclides in the dust fraction are relatively low in comparison ICRP reference level.

Geochemistry of uranium and thorium in phosphate deposits at the Syrian coastal area (Al-Haffah and Al-Qaradaha) and their environmental impacts

The aim of this research was to study the geochemistry of uranium and thorium in phosphate deposits in the upper Cretaceous phosphate deposits in the Syrian coastal area. The study covered three sites, namely Ain Al-Tenah, Ain Laylon, and Al-Mhalbeh. Petrographical study showed that phosphate deposits are of nodular type with micrit to microspaite cement, containing siliceous bone residues, and green grains of glauconite, which are increasing in abundance and volume in the south toward Al-Mhalbeh, reflecting the formation of phosphate in a shallow marine environment. In addition, uranium concentration varied between 3 and 112 ppm in Ain Laylon, 4.2-17 ppm in Ain Al-Tenah and 5-61 ppm in Al-Mhalbeh. Thorium concentration varied between 0.2 and 7.5 ppm in Ain Laylon, 0.3-1.4 ppm in Ain Al-Tenah and 0.3-4.4 ppm in Al-Mhalbeh. The average Th/U ratio in the collected samples was within the range 0.04-0.08 except for five samples which exceeded the value 0.1. Moreover, the ²²⁶Ra/²³⁸U ratios are lower than unity in all samples, while the ²¹⁰Pb/²³⁸U ratios ranged between 0.4 and 1.2 and the ²¹⁰Pb/²²⁶Ra ratios were found to be higher than unity. On the other hand, the impact of leaching and mobility of uranium and thorium from deposits to the surrounding agriculture fields in the area has been studied using the Radium Equivalent Activity Index (Ra_eq). The equivalent radium activity was 102 Bq kg^-1 in Ain Al-Tenah, 403 Bq kg^-1 in Ain Laylon, 407 Bq kg^-1 in Al-Mhalbeh and 749 Bq kg^-1 in agricultural soil samples. However, the data reported in this study can be considered as a baseline data for the phosphate deposits at the coastal area.

Depleted uranium assessment and natural radioactivity monitoring in North West of Iraq over a decade since the last Gulf War

For the sake of completeness of the surveillance process concerning the spread of depleted uranium (DU) in the Arabian Gulf region, we have applied a simple gamma spectroscopy technique to evaluate its content in Al Jolan, Nazzal and Askari districts in Al Fallujah area, Iraq for the first time and after more than one decade. The measurements were carried out along the lines of the wars that have been witnessed in Iraq last period and expected to be the region of impact of residuals of a large quantity of DU. The observed radionuclides are ⁴ K and other naturally occurring radioactive members of uranium and thorium series. The obtained results show that, the average specific activity concentrations of ²²⁶Ra, ²³²Th, ⁴ K, ²¹⁰Pb ²³⁸U and ²³⁵U in different soil samples collected from Al Fallujah area, Iraq in range of 20.09 ± 4.0 to 21.94 ± 2.4, 11.51 ± 2.3 to 11.75 ± 3.2, 96.53 ± 8.0 to 112.13 ± 49.8, 19.98 ± 4.6 to 20.76 ± 4.8, 25.4 ± 3.9 to 26.1 ± 6.0 and 1.28 ± 0.18 to 1.34 ± 0.21 respectively. The obtained values of Ra_eq for all the investigated samples are less than the recommended limit of 370 Bq kg^-1 and those for H_ex are less than one. These results have been compared with the previous works and the world mean values specified by the UNSCEAR reports. The mean ratio of ²³⁸U/²³⁵U activity in all cases is about the natural value (21.73) which is less than its value in case of DU (76.92). The present obtained results of DU levels show that although a large amount of DU was released in Iraq during the Gulf wars, the tested samples are DU free. This may be attributed to the reduction of DU from the soil surface by wind or sandstorms and the downward leaching process.

Radioactivity levels and health risks due to radionuclides in the soil and sediment of mid-Black Sea: Kızılırmak Deltas-Turkey

Artificial and natural radionuclide pollutants of the marine environment have been recognized as a serious environmental concern. In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil and sediment samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI (Tl) detector. The average specific of activity concentrations for 238U, 232Th and 40K were found to be 28.59, 17.48 and 150.59 Bq kg−1, respectively. On the other hand, 137Cs was also measured in some samples. 137Cs (t1/2=30.17 years) is a man-made radionuclide released from nuclear fission and activation processes. It has a mean value of 5.32 Bq kg−1. From the activity concentrations, the radium equivalent activity (Raeq), the absorbed gamma dose rates (DR), the annual gonadal dose equivalent, annual effective dose equivalent, internal (Hin), external hazard index (Hex) and excess lifetime cancer risk were estimated. This study can be used as a base line for future investigations and the data obtained in this study may be useful for natural radioactivity mapping and also be used as a reference data for monitoring possible radioactivity pollutions in future.

Analysis of the natural radioactivity concentrations of the fine dust samples in Jeju Island, Korea and the annual effective radiation dose by inhalation

This study analyzed the concentrations of potassium, thorium and uranium of the atmospheric PM₁₀ aerosols which were collected at Gosan of Jeju Island during the year of 2014. The mean mass concentration of PM₁₀ was 47.31 μg/m³. The mean radioactive concentrations of ⁴⁰K, ²³²Th and ²³⁸U were 7.89, 0.25 and 0.30 μBq/m³, respectively. The ²³²Th/²³⁸U activity concentration ratio of PM₁₀ was 0.830. The ²³²Th/²³⁸U ratio during Asian Dust days is 1.073, which is higher than those in other atmospheric conditions. The concentration ratio of ²³²Th/²³⁸U was 0.902 in China continent.

Natural radioactivity-based radiological hazards in soils of the islands: a case study from Eastern Turkey

A comprehensive work was carried out to investigate natural radionuclides of 238U, 232Th and 40K in 73 soil samples collected from islands of Adır, Çarpanak and Akdamar on the Van Lake (Turkey) located at Eastern Turkey. Radioactivity concentrations of these radionuclides were measured by using a gamma spectrometer with NaI(Tl) detector to be from 4.11 to 77.1 Bq/kg, from 6.0 to 70.0 Bq/kg and from 133.05 to 749.77 Bq/kg with the mean values of 33.33 Bq/kg, 36.68 Bq/kg and 478.19 Bq/kg, respectively. In addition, the absorbed gamma dose rate in air (D) and annual effective dose equivalent (AED) were found to be 57.5 nGy/h and 70.5 μSv/year, respectively. We have shown that our results might be related to the geological formation type. The results were compared with some published ones in Turkey and the World, which were found within acceptable limits.

Assessment of radiological hazard parameters due to natural radioactivity in soils from granite-rich regions in Kütahya Province, Turkey

The analysis of natural radioactivity from ²³⁸U, ²³²Th and ⁴⁰K in 357 soil samples collected from the province of Kütahya was carried out using a NaI(Tl) gamma-ray spectroscopy system at the Nuclear Physics Research Laboratory, Dumlupınar University, Kütahya, Turkey. The specific activities of ²³⁸U, ²³²Th and ⁴⁰K in the soil samples were evaluated. From the activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K, the total absorbed outdoor gamma-ray dose rates and the corresponding annual effective dose rates were determined. The corresponding values of the external and internal hazard indices of all the soil samples were also calculated. The external gamma-ray dose rate at 1 m above the ground was directly measured at each collected soil sample location. The results obtained in this study were compared within the limits of values obtained in other cities of Turkey, those in other countries. Radiological maps of Kütahya Province were constructed from the results of this study.

Radiological impact assessment to the environment due to waste from disposal of porcelain

The present study aimed to assess the radiological parameters from gamma rays due to the uncontrolled disposal of porcelain waste to the environment. Qualitative and quantitative identification of radionuclides in the investigated samples was carried out by means of a high-purity germanium (HPGe) detector. The average activity concentrations of the local porcelain samples were measured as 208.28 Bq/kg for ²²⁶Ra, 125.73 Bq/kg for ²³⁸U, 84.94 Bq/kg for ²³²Th and 1033.61 Bq/kg for ⁴⁰K, respectively. The imported samples had an average activity of 240.57 Bq/kg for ²²⁶Ra, 135.56 Bq/kg for ²³⁸U, 115.74 Bq/kg for ²³²Th and 1312.49 Bq/kg for ⁴⁰K, respectively. Radiological parameters and the radium equivalent Ra_eq for the investigated samples were calculated. The external and internal hazard indices, representative level index (I_γ), alpha index (I_α), and the exemption level (I_x), were estimated to be higher than the recommended value (unity), while the average activity concentrations for the studied samples were higher than recommended levels. In conclusion, we are concerned that disposal of porcelain in the environment might be a significant hazard.

Determination of (226)Ra, (232)Th, (40)K, (235)U and (238)U activity concentration and public dose assessment in soil samples from bauxite core deposits in Western Cameroon

Determination of activity concentrations in twenty five (25) soil samples collected from various points in bauxite ore deposit in Menoua Division in Western of Cameroon was done using gamma spectrometry based Broad Energy Germanium (BEGe6530) detector. The average terrestrial radionuclides of (40)K, (226)Ra, (232)Th, (235)U and (238)U were measured as 671 ± 272, 125 ± 58, 157 ± 67, 6 ± 3 and 99 ± 69 Bq kg(-1), respectively. The observed activity concentrations of radionuclides were compared with other published values in the world. The outdoor absorbed dose rate in air varied from 96.1 to 321.2 nGy h(-1) with an average of 188.2 ± 59.4 nGy h(-1). The external annual effective dose rate and external hazard index were estimated as 0.23 ± 0.07 mSv year(-1) for outdoor, 0.92 ± 0.29 mSv year(-1) for indoor and 1.13 for the external hazard index, respectively. These radiological safe parameters were relatively higher than the recommended safe limits of UNSCEAR. Consequently, using of soil as building material might lead to an increase the external exposure to natural radioactivity and future applications research need to be conducted to have a global view of radioactivity level in the area before any undergoing bauxite ore exploitation.

Soil radioactivity levels, radiological maps and risk assessment for the state of Kuwait

An evaluation of the radioactivity levels associated with naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a surface radiological map of the State of Kuwait. Soil samples from across Kuwait were collected, measured and analysed in the current work. These evaluations provided soil activity concentration levels for primordial radionuclides, specifically members of the (238)U and (232)Th decay chains and (40)K which. The (238)U and (232)Th chain radionuclides and (40)K activity concentration values ranged between 5.9 ↔ 32.3, 3.5 ↔ 27.3, and 74 ↔ 698 Bq/kg respectively. The evaluated average specific activity concentrations of (238)U, (232)Th and (40)K across all of the soil samples have mean values of 18, 15 and 385 Bq/kg respectively, all falling below the worldwide mean values of 35, 40 and 400 Bq/kg respectively. The radiological risk factors are associated with a mean of 33.16 ± 2.46 nG/h and 68.5 ± 5.09 Bq/kg for the external dose rate and Radium equivalent respectively. The measured annual dose rates for all samples gives rise to a mean value of 40.8 ± 3.0 μSv/y while the internal and internal hazard indices have been found to be 0.23 ± 0.02 and 0.19 ± 0.01 respectively.

Determination of 40K, 232Th and 238U activity concentrations in ambient PM2.5 aerosols and the associated inhalation effective dose to the public in Jeddah City, Saudi Arabia

Natural radioactivity of soil samples has been studied in many countries of the Arabian Peninsula, including Saudi Arabia. Radiological indices based on soil radioactivity have been widely used in these studies. However, there are no available data about natural radioactivity of fine aerosol particles in such countries. The objective of this study is to determine the activity concentrations of (40)K, (232)Th and (238)U in airborne PM2.5 and the associated internal inhalation radiation dose to the public in Jeddah City, Saudi Arabia. Twenty-four air samples in four locations throughout Jeddah were collected and analyzed for PM2.5 and the associated K, Th and U. The activity concentrations of the isotopes (40)K, (232)Th and (238)U were calculated. High atmospheric PM2.5 concentrations (mean: 50.81 ± 34.02 μg/m(3)) were found. The natural radioactivity associated with PM2.5 due to the isotopes (40)K, (232)Th and (238)U were 301.8 ± 76.1, 11.8 ± 4.2 and 10.8 ± 3.4 Bq/kg, respectively, and the Raeq was calculated as 44.9 ± 14.0 Bq/kg. The inhalation annual effective radiation dose to the public due to natural isotopes of the airborne PM2.5 was in the range 15.03-58.87 nSv/year, depending on the age group. Although these dose values were associated with the PM2.5 fraction only, they were higher than the world references values in air reported in the UNSCEAR, 2000 report.

Study of natural radioactivity and estimation of radiation dose in the environment of Tumkur, Karnataka, India

The activity concentration of (226)Ra, (232)Th and (40)K was measured for soil samples collected from 34 locations of Tumkur District, Karnataka, India, using HPGe detector. The activity concentration of (226)Ra, (232)Th and (40)K varied from 9.6 to 71.6, 12.3 to 333.3 and 194.3 to 1527.7 Bq kg(-1) with an average value of 33.15, 123.01 and 877.76 Bq kg(-1), respectively. The absorbed and annual effective outdoor doses were found to be highest at Ponnasamudra with 258.98 nGy h(-1) and 317.62 μSv and lowest at Sira with 36.42 nGy h(-1) and 44.67 μSv, respectively. The external hazard index ranged from 0.21 to 1.58 with an average of 0.75. It was significant in 11 locations as it exceeded unity.

Determination of natural and artificial radioactivity in soil at North Lebanon province

The concentrations of natural and artificial radionuclides at 57 sampling locations along the North Province of Lebanon are reported. The samples were collected from uncultivated areas in a region not previously reported. The samples were analyzed by gamma spectrometers with High Purity Germanium detectors of 30% and 40% relative efficiency. The activity concentrations of primordial naturally occurring radionuclides of (238)U, (232)Th, and (40)K varied between 4-73 Bq kg(-1), 5-50 Bq kg(-1), and 57-554 Bq kg(-1) respectively. The surface activity concentrations due to the presence of these radionuclides were calculated and Kriging-geostatistical method was used to plot the obtained data on the Lebanese radioactive map. The results for (238)U, (232)Th, and (40)K ranged from 0.2 kBq m(-2) to 9 kBq m(-2), from 0.2 kBq m(-2) to 3 kBq m(-2), and from 3 kBq m(-2) to 29 kBq m(-2) respectively. For the anthropogenic radionuclides, the activity concentrations of (137)Cs founded in soil ranged from 2 Bq kg(-1) to 113 Bq kg(-1), and the surface activity concentration from 0.1 kBq m(-2) to 5 kBq m(-2). The total absorbed gamma dose rates in air from natural and artificial radionuclides in these locations were calculated. The minimum value was 6 nGy h(-1) and the highest one was 135 nGy h(-1) with an average of 55 nGy h(-1) in which the natural terrestrial radiation contributes in 99% and the artificial radionuclides mainly (137)Cs contributes only in 1%. The total effective dose calculated varied in the range of 7 μSv y(-1) and 166 μSv y(-1) while the average value was 69 μSv y(-1) which is below the permissible limit 1000 μSv y(-1).

Measurement of the terrestrial and anthropogenic radionuclide concentrations in Bafra Kizilirmak delta (bird sanctuary) in Turkey

In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI(Tl) detector. The average values of activity concentrations of (238)U, (232)Th and (40)K were found to be 37.2±2.8, 33.7±3.1 and 413.0±59.8 Bq kg(-1), respectively. (137)Cs was also measured in some samples. It has a mean value of 13.8±1.0 Bq kg(-1). From the activity concentrations, the absorbed gamma dose rates in outdoor and the corresponding annual effective dose rates and external hazard index (Hex) were estimated.

A survey of distribution of terrestrial radionuclides in surface soil samples in and around the Osmaniyeprovince, Turkey

The purpose of this survey was to determine the distribution of terrestrial radionuclides ((238)U, (232)Th and (40)K) in surface soil samples collected from different locations in and around Osmaniye and assess the radiological implications of outdoor external exposure. The activity concentrations of (238)U, (232)Th and (40)K in soil samples ranged from 2.6 to 38.1 Bq kg(-1) with a mean of 10.4±0.7 Bq kg(-1), 3.7-40.5 Bq kg(-1) with a mean of 12.2±0.7 Bq kg(-1) and 30.0-639.7 Bq kg(-1) with a mean of 243.4±12.8 Bq kg(-1), respectively. The concentrations of these radionuclides, presented in this article, were compared with those obtained from similar studies related to Turkey reported in the literature as well as earth's crust average values. The results of the activity concentrations were used to assess the external absorbed gamma dose rate (GDR) in outdoor air and the annual effective dose (AED). The outdoor absorbed GDRs fluctuate from 5.2 to 53.6 nGy h(-1) with a mean of 22.4±9.5. The corresponding mean AED is found to be 0.03 mSv.

The effects of physicochemical properties on gamma emitting natural radionuclide levels in the soil profile of Istanbul

The inventory of gamma-emitting radionuclides was determined in soil samples collected at six depth levels, from 15 locations in Istanbul metropolis. The activity concentrations of (232)Th, (238)U, (40)K were measured by means of gamma spectrometry. The average activity concentrations of (232)Th, (238)U, (40)K in the 30-cm depth soil were found as 32.1, 27.4, 393.1 Bq kg(-1), respectively. The mean value of the absorbed dose rate (D), annual effective dose equivalent (AEDE) from the outdoor terrestrial gamma radiation, Ra equivalent activity (Ra(eq)), and the external hazard index (H(ex)) were calculated as 48.7 nGy h(-1), 59.7 muSv, 104.1 Bq kg(-1), and 0.28, respectively. The effects of organic matter content, textural properties, and pH value of soil samples on the natural radionuclide levels were also investigated. The relations between natural radionuclide level and the physical and chemical properties of studied soil samples were mainly clarified with cluster analysis and Pearson correlation.

Distribution of some natural and man-made radionuclides in soil from the city of Veles (Republic of Macedonia) and its environs

A systematic study of soil radioactivity in the metallurgical centre of the Republic of Macedonia, the city of Veles and its environs, was carried out. The measurement of the radioactivity was performed in 55 samples from evenly distributed sampling sites. The gross alpha and gross beta radioactivity measurements were made as a screening, using a low background gas-flow proportional counter. For the analysis of (40)K, (238)U, (232)Th and (137)Cs, a P-type coaxial high purity germanium detector was used. The values for the activity concentrations of the natural radionuclides fall well within the worldwide range as reported in the literature. It is shown that the activity of man-made radionuclides, except for (137)Cs, is below the detection limit. (137)Cs originated from the atmospheric deposition and present in soil in the activity concentration range of 2-358 Bq kg(-1) is irregularly distributed over the sampled territory owing to the complicated orography of the land. The results of gamma spectrometry are compared to the K, U, and Th concentrations previously obtained by the reactor neutron activation analysis in the same soil samples.